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Commit c6f67a1f authored by Octavian Purdila's avatar Octavian Purdila Committed by Jonathan Cameron
Browse files

iio: allow userspace to flush the hwfifo with non-blocking reads 



This patch changes the semantics of non-blocking reads so that a
hardware fifo flush is triggered if the available data in the device
buffer is less then the requested size.

This allows userspace to accurately generate hardware fifo flushes, by
doing a non-blocking read with a size greater then the sum of the
device buffer and hardware fifo size.

Signed-off-by: default avatarOctavian Purdila <octavian.purdila@intel.com>
Reviewed-by: default avatarLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: default avatarJonathan Cameron <jic23@kernel.org>
parent e20008ed

drivers/iio/industrialio-buffer.c

+9 −9
Original line number Diff line number Diff line
@@ -71,8 +71,9 @@ static bool iio_buffer_ready(struct iio_dev *indio_dev, struct iio_buffer *buf, 


	if (avail >= to_wait) {

		/* force a flush for non-blocking reads */

		if (!to_wait && !avail && to_flush)

			iio_buffer_flush_hwfifo(indio_dev, buf, to_flush);

		if (!to_wait && avail < to_flush)

			iio_buffer_flush_hwfifo(indio_dev, buf,

						to_flush - avail);

		return true;

	}
@@ -100,8 +101,7 @@ ssize_t iio_buffer_read_first_n_outer(struct file *filp, char __user *buf, 
	struct iio_dev *indio_dev = filp->private_data;

	struct iio_buffer *rb = indio_dev->buffer;

	size_t datum_size;

	size_t to_wait = 0;

	size_t to_read;

	size_t to_wait;

	int ret;



	if (!indio_dev->info)
@@ -119,14 +119,14 @@ ssize_t iio_buffer_read_first_n_outer(struct file *filp, char __user *buf, 
	if (!datum_size)

		return 0;



	to_read = min_t(size_t, n / datum_size, rb->watermark);



	if (!(filp->f_flags & O_NONBLOCK))

		to_wait = to_read;

	if (filp->f_flags & O_NONBLOCK)

		to_wait = 0;

	else

		to_wait = min_t(size_t, n / datum_size, rb->watermark);



	do {

		ret = wait_event_interruptible(rb->pollq,

			iio_buffer_ready(indio_dev, rb, to_wait, to_read));

		      iio_buffer_ready(indio_dev, rb, to_wait, n / datum_size));

		if (ret)

			return ret;